Accumulation and partitioning of mineral nutrients in wheat as influenced by nitrogen form

The form of nitrogen (N) [e.g., nitrate (NO₃^-) and ammonium (NH₄⁺)] available to plants affects many growth processes, including mineral nutrient acquisition. The objective of this study was to assess the effects of N form on the accumulation and partitioning of mineral nutrients in wheat. Two species of spring wheat (Triticum aestivum L. cv. Len and Triticum durum Desf. cv. Inbar) were grown hydroponically in the greenhouse with N supplied as either all NO₃^-, or all NH₄⁺, or an equal mixture of the two forms (mixed N). Plants were harvested after 21 days of growth, divided into shoots and roots and each part analyzed for nine mineral elements [phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and boron (B)]. The accumulation and partitioning of the mineral nutrients was dependent on the wheat species, the N form, and the nature of the ion. Inbar plants always accumulated more of each element than did Len. Compared with all NO₃^- nutrition, mixed N increased the whole plant and/or shoot accumulation of P, K, Cu, and B, but not Ca, Mg, Fe, Mn, and Zn; while all NH₄⁺ decreased these values for most elements. With few exceptions, N form did not affect either the accumulation or partitioning of Mg and Fe. Plants grown with all NO₃^- accumulated more Mn and Zn than those receiving mixed N or all NH₄⁺, while the partitioning of both ions was not affected by N form. When grown with mixed N or all NH₄⁺, less P, K, Cu, and B was partitioned to the roots compared to plants receiving all NO₃^-. These results demonstrate the differential effects of N form on mineral nutrient acquisition and nutrient use by wheat, which may be related to N-form induced differences in plant growth.